Hi all, the contributed function package Wilcoxon.gfn is going to be removed from the server soon. Gretl covers the functionality (the signed rank Wilcoxon test) with the built-in command 'difftest'. Example usage for series x and y (see also the difftest help): difftest x y --signed-rank And you can retrieve the results via the usual $test and $pvalue accessors. If you need a functional form, you could use something like this trivial wrapper: <hansl> function scalar wilcoxonreplacement(series x, series y) difftest x y --signed-rank return $test end function </hansl> In the graphical interface (GUI) you would go to: Tools/Nonparametric tests/ Difference test. Happy testing, Sven